Gas absorption refrigerators/space coolers are commonly used in areas with erratic or no electricity in order to provide cooling or refrigeration. The principle of operation is that a gas may be absorbed into a liquid (thus the name), then boiled out as needed, sent through an expansion process to produce adiabatic cooling via the Joule-Thomson or Joule-Kelvin effect: the expanding gas cools, then passes through cooling coils which provide a net cooling output from the overall device. After the expansion, the gas must be absorbed again.
There are various types of gas absorption refrigerators: single working fluid types, double working fluid types, gravity feed devices using no pumps, cyclic and continuous and so on. The cyclic type having a fluid, a gas and an electrically driven pump is easiest to produce but is fairly complex: an electrically driven pump (or compressor) is the operative moving part in traditional refrigerators/air conditioners and thus to a certain extent it's presence defeats the advantages of a gas absorption refrigerator in the first place.
The internal workings of traditional gas absorption refrigerators will be discussed in detail in reference to FIG. 1 in the DETAILED DESCRIPTION portion of this application.
Searching in the collection of the US Patent and Trademark Office reveals certain items of interest.
US Patent Publication No. 2005/0132724 published Jun. 23, 2005 in the name of Sharma et al teaches a gas absorption device which uses multiple stages or “multiple effect” operation in order to attempt to produce higher efficiencies and reduced heat requirements. U.S. Pat. No. 4,183,228 issued Jan. 15, 1980 to Saito et al is similar in basic principle of double stage operation, as does U.S. Pat. No. 4,085,595 issued Apr. 25, 1978 to Saito et al.
US Patent Publication No. 2005/0044864 published Mar. 3, 2005 in the name of Manole et al teaches a fluid flow design in which a working fluid may expand or contract based upon heat input thereto.
U.S. Pat. No. 5,943,686 issued Aug. 21, 1999 in the name of Dietz et al teaches a gas absorption device using solar energy and a continuous cycle of operation, without a moving generator or combined generator/absorber structure.
U.S. Pat. No. 3,986,341 issued Oct. 19, 1976 to DeHann teaches a spiral winding for a low heat loss heat shield.
U.S. Pat. No. 4,363,219 issued Dec. 14, 1982 to Koseki et al teaches a gas absorption device which uses a three liquid system: the intermediate liquid has favorable thermodynamic properties for the system.
U.S. Pat. No. 5,181,391 issued Jan. 26, 1993 to Manz teaches a conventional (non-gas absorption) refrigeration handling system which happens to have a pressure gauge thereon and extra refrigerant handling equipment, as does U.S. Pat. No. 5,063,749 issued Nov. 12, 1991 to the same inventor.
U.S. Pat. No. 4,788,829 issued Dec. 6, 1988 to Takemasa et al teaches another two-stage system of mixed refrigerant type.
U.S. Pat. No. 4,700,545 issued Oct. 20, 1987 to Ishibashi et al teaches a pair of mechanically driven expansion spaces for a refrigerator device.
U.S. Pat. No. 4,475,353 issued Oct. 19, 1984 to Lazare teaches a serial gas absorption system offering low temperatures but using various electrical and controlled parts. U.S. Pat. No. 3,817,050 issued to Alexander et al on Jun. 18, 1974 actually teaches a three stage device.
U.S. Pat. No. 3,815,379 to Hoenisch issued Jun. 11, 1974 teaches a device having a fan control system, the fan and system are both electrical, as does U.S. Pat. No. 3,811,292 to the same inventor on May 21, 1974, and U.S. Pat. No. 3,707,851 issued to McAshan, Jr. on Jan. 2, 1973, and U.S. Pat. No. 4,991,404 issued Feb. 12, 1991 to Yassa.
U.S. Pat. No. 3,555,841 issued on Jan. 19, 1971 to Modahl et al teaches a corrosion resistant method and a large and complex industrial gas absorption device.
All of these devices in the gas absorption field teach in the direction of increased complexity, multiple stages to increase efficiency, serial refrigeration systems to increase output, complex controls and so on. Devices not relevant to gas absorption technology teach heat shielding and the like. None teach in the direction of simpler, physically automatic and therefore autonomous refrigeration systems which require no electricity at all to operate in a non-continuous mode.
It would be preferable to provide a gas absorption device which does not require electrical control over any part of the operation, does not require control over the heat source, does not require electricity supply to a pump or fan, and yet can operate autonomously in a cyclic mode of operation.
It would be preferable to provide a gas absorption device able to use the heat source to move the working parts as needed to maintain efficient cyclic operation.
It would further be preferable to provide a gas absorption refrigeration/cooling device having high efficiency of operation.
It would further be preferable to provide a gas absorption device able to use a single vessel as both generator and absorptive chamber, with a wide variety of working and absorptive liquids.
Finally, it would be preferable to provide a gas absorption device offering easy construction and maintenance.